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Date: 26 Aug 93 16:54:24 GMT
From: cis.ohio-state.edu!magnus.acs.ohio-state.edu!usenet.ins.cwru.edu!howland.
reston.ans.net!vixen.cso.uiuc.edu!cs.uiuc.edu!cs.uiuc.edu!rowe@ucbvax.Berkeley.
EDU  (Kenneth E. Rowe)
Subject: Re: How to assign STRINGs?
Message-ID: <CCDLMo.A8D@cs.uiuc.edu>
List-Id: <comp.lang.ada>

In article <1993Aug25.121754.20413@hellgate.utah.edu> matwood%peruvian.cs.utah.
edu@cs.utah.edu (Mark Atwood) writes:
>
>I'm kind of embarrassed asking this, after using Ada for over a year, but
>I was never very clear on unconstrained arrays, and now it's bitten me.
>
>Here is some representative code.
>
>
>  function GET_PARM return STRING;
>  -- from the vendor supplied DOS package
>
>  with TEXT_IO;
>  procedure ECHO is
>    subtype STR is STRING(1 .. 255);
>    CMDLINE : STR;
>  begin
>    CMDLINE := DOS.GET_PARMS;   -- get a CONTRAINT_ERROR here
>    TEXT_IO.PUT_LINE (CMDLINE);
>  end ECHO;
>
>
>So, how DO i assign the results of a function returning an unconstrained
>string to a constrained string?
>
>-- 
>Mark Atwood                  | My school and employer have too many problems
>matwood@peruvian.cs.utah.edu | without being blamed for mine.

have you tried
    CMDLINE (1..255) := Dos.Get_Parms;  
???

if so then you can use the text_io routines that use a string as input and pars
es it out.  

Unfortunately, all the "normal" tricks with array slices doesn't work when
a function has side effects (2 calls in a row give different results).

normally you can just do:
  cmdline(1..(dos.get_parms)'length) := dos.get_parms;
**** but ONLY if dos.get_parms doesn't change between the two calls.

Hopefully there is just an over-sight in the documentation on 
dos.get_parms.  Try the first example and see what happens.

Ken.